Virtual terminal (VT)

Virtual terminal (VT) is a kind of offer is similar to Internet Telnet agreement remote terminal simulation of the international organization for standardization (ISO) agreement. In a remote terminal users, can be in remote to run on a computer applications, as though they were sitting in front of the computer is same.

Virtual terminal is in a personal computer virtual a terminal and for this purpose writing software. Virtual terminal purpose is to achieve personal computers and users can with large computer connections. Generally required to connect large computer is IBM mainframe computer or so-called small-sized computer (past is often di taanach VAX).

Virtual terminal make personal computer users can directly use his personal computers with large computer contact, without the use of special terminal.

Through the virtual terminal software virtual terminal can also expand large computer standard terminal function, through the virtual terminal can not only will the data transfer on personal computers to large computers, and can also bring large computer data transfer to the personal computer, and the PC continue processing.

General large computer terminal is letters type of input and output interface, so a virtual terminal should have at least one can simulate such letters type (such as ASCII) input and output interface ability. The most common platform is the user surface. Image type To make the new, image type program can use the old letters type or no image type input and output capacity of program also need virtual terminal.

Modern large computer also internal use virtual terminal, so they can ask old and require terminal program pretend a terminal, but in fact it is a program's display turned to display adapters. For instance Linux and most other pc-based similar Unix operating system pretend to have six to ten such "virtual" of the terminal.

Letters program < - > virtual terminal < - > image display

Shells < - > xterm < - > X11

structure

Virtual terminal makes a letter type programs can be a graphical user interface and the user communication. Them so that the user can use cannot directly using image interface program (for example, because they haven't image when programming interface, or because the letters type interface is simpler). Virtual terminal to letters type program "pretended" give a letter terminals while to image interface "pretended" give a image type of program.

Working way

Virtual terminal to complete a terminal program task. But a virtual terminal is a common, in an operating system, the computer CPU run on ordinary procedure, rather than a stored in terminal read-only memory of, in the terminal CPU operation of the procedure. Virtual terminal analysis of a letter to type the program's output, convert it to image interface (such as X11) output.

The terminal window inside the keyboard input transfer to large computer with terminal connections trip, general this trip is a command-line interpreter. This journey think oneself is connected with a terminal, but in fact it is connected with a virtual terminal.